1, 2-dihalo-delta-cycloalkenes



Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE 1,2-DIHAL-DELTA -GYOLOALKENES No Drawing. Application August 24, 1937, Serial No. 160,606

9 Claims.

' Continuation in part of application Serial No. 744,198, filed September 15, 1934.

This invention relates to, and has for its object the provision of, 1,2-dihalo-delta -cyc1oalkenes having or 6 carbon atoms in the ring. These compounds may be prepared by treating the corresponding 1,2,3-trihalo-cyc1oalkane with a dehydrohalogenating agent such as potassium hydroxide, sodium hydroxide, or quinoline. These 1,2-dihalo-delta -cycloalkenes are useful as intermediates in the preparation of hypnotics.

The following examples are illustrative of the invention:

15 Example 1.1,2-dibromo-delta -cyclohexene 100 g. (1 mol) 1,2,3-tribromo-cyclohexane [obtainable from l-brom delta -tetrahydrobenzene (Crossley, .1. Chem. Soc. 85, 1422), by adding bromine thereto to form a tribromide (Zelinsky and Gorski, Ber. 44, 2312)] and 26.5 g. (1.5 mols) of crushed potassium hydroxide are heated in a Claisen flask on the steam bath, while evacuating the system. A vigorous reaction ensues withrapid distillation at about 40 mm. The distillate is dis- 25 solved in ether, the solution dried over sodium sulfate, the ether removed, and the residual oil rectified. The 1,2-dibromo-delta -cyclohexene obtained is a colorless oil having a boiling point of 110-111 C. at 7 mm.

Example 2.--1,2-dibr0m0delta -cyclope'ntene 50 g. 1,2,3-tribromo-cyclopentane [obtainable by adding HBrto cyclopentadiene to form l-bromdelta -cyclopentene (of. J. Chem. Soc., 85, 1422),

3 and adding bromine thereto to form a tribromide (of. Ber. 44, 2312)] and 12.5 g. of crushed potassium hydroxide are heated in a Claisen flask, while evacuating the system. A vigorous reaction ensues with rapid distillation at about 40 mm. The distillate is dried over calcium chloride and recti- 5 fied. The 1,2-dibromo-delta -cyclopentene obtained is a colorless oil having a boiling point of 78-79" C. at 5 mm.

The invention may be variously otherwise embodied within the scope of the appended claims.

I claim:

1. 1,2.-dihalo-delta -cycloa1kenes having 5 to 6 carbon atoms in the ring. v

2. 1,2-dibromo-delta cyc10a1kenes having 5 to 6 carbon atoms in the ring.

3. 1,2-dihalo-delta -cyclopentene.

4. 1,2-dibromo-delta -cyclopentene.

5. 1,2-dihalo-delta -cyclohexene.

6. 1,2-dibromo-delta -cyclohexene.

7. The process of preparing 1,2-dihalo-delt'a cycloalkenes having 5 to 6 carbon atoms in the ring, which comprises reacting the corresponding 1,2,3-trihalo-cycloalkane with a de-hydrohalogehating agent.

8. The process of preparing 1,2-dibromo-de1ta cycloalkenes having 5 to 6 carbon atoms in the ring, which comprises reacting the corresponding 1,2,3-tribromo-cycloalkane with a de-hydrohalogenating agent.

9. The process of preparing 1,2-dibromo-de1ta cycloalkenes having 5 to .6 carbon atoms in the ring, which comprises reacting the corresponding 1,2,3-tribromo-cycloa1kane with potassium hydro oxide.

WALTER G. CHRIS'IIANSEN. 

